"We now have the remains of at least seven hobbit-sized individuals at the cave site, so the 18,000-year-old skeleton cannot be some kind of 'freak' that we just happened to stumble across first," said Bert Roberts, an anthropologist at the University of Wollongong in New South Wales, Australia, and co-author of the study about the find in this week's issue of the journal "Nature."

Peter Brown, lead researcher of the study and an anthropologist at the University of New England in Armidale, Australia, says that although modern humans had reached Australia by 45,000 years ago, so far there's no evidence suggesting the small species of human and modern humans ever met.

Still, another author, Mike Morwood, also of the University of New England, says because the two existed in the same general region for nearly 30,000 years, "It is certain that they came face to face on occasion."

Island Adaptation

Although the odd little humans likely left no descendants, and therefore no mark on modern human biology, the scientists say this is the first documentation of the entirely new species of hominins that apparently adapted and lived for thousands of years in caves on the isolated island. As for their size, their limited habitat and its hot, humid conditions may have been key factors.

Brown and the other authors suggest that the newly found species, named Homo floresiensis, arrived on the island of Flores, in Indonesia's Nusa Tenggara region, in the form of Homo erectus, the first large-brained hominin that emerged some 2 million years ago in Africa and Asia.

Morwood has argued that Homo erectus reached the island by building some kind of water vessel since Flores was likely never connected to the mainland by a land bar. No evidence of a prehistoric boat has been found on the island, however, and many scientists remain skeptical that primitive man could manage the feat. But besides swimming (which is unlikely), the only other known possibility would be rafting -- catching a ride on a micro-island that had broken off a mainland. And anthropologists say this probably would not have worked for a large creature like Homo erectus.

"It's hard to imagine humans being rafted in that way," said Rick Potts, curator of the Institute of Human Origins at the Smithsonian Institution in Washington. "The idea of how they got there is still very much in the air."

However Homo erectus got to the island, once it arrived, Brown suggests its generations began to shrink in size. Fossils show that Homo erectus was fairly tall, standing, on average, 5 feet 10 inches. On Flores, due to the limited resources on the 31-square-mile island, smaller versions of the hominin may have survived best, since they would have required less food to survive. This could have led to the evolution of the new, miniature species.

Hot and humid weather on the island could also have favored smaller bodies in the same way it may have led to the small size of Pygmy populations who live in tropical forests of Africa. The theory is since the surface area of a small body is greater in relation to its volume, it's easier to cool off. Plus, less energy is needed to move a small person's body weight, so less heat is generated.

Similar factors were probably also at play to favor the pint-sized Stegodon, whose remains were found in the same cave as the tiny person. Evidence suggests the dwarfed people may have hunted the miniature elephant-like creatures in groups. The authors point to an array of stone tools, also found in the cave, which were likely used in the hunt and to butcher prey. Remains of a Komodo dragon, an oversized lizard that still roams the island today, were also found in the cave, along with charred bones of birds, rats and fish suggesting they may have been cooked and eaten by the small humans.

Tiny Brains

More puzzling than their body size, however, is the apparently puny size of the early humans' brains. Today, the average human brain measures between 1,400 and 1,500 cubic centimeters. Homo erectus had a skull that packed a brain about two-thirds the size of today's human brains, or about 800-1,000 cubic centimeters. The skull found on Flores suggests these small humans operated with a brain only 380 cubic centimeters in size -- the smallest known brain of any known hominin species.

Despite their brains' diminutive size, Homo floresiensis was apparently smart enough to make and use tools, use fire and to find the ideal shelter of the limestone cave.

"The fact that it had these behavioral associations with such a small cranial capacity is astounding," said Potts. "It's a little weird."

Despite the puzzlingly small brain size, Potts calls the discovery "terrific" and the research "convincing," although he adds that a team of paleo-anthropologists will need to see the bones and travel to the site in order for the science community to reach a consensus about adding a new branch to the already bushy tree of human evolution.

Evolutionary Tree Gets Bushier

Other anthropologists are skeptical that the find is all it is cracked up to be. Yohannes Haile-Selassie, curator at the Cleveland Museum of Natural History in Ohio, thinks naming it a new species is premature.

"I have mixed feelings about this whole thing," he said. "This is one specimen. It could have a small body and brain size due to disease or pathology."

In fact, many anthropologists have argued that in recent years, scientists have been adding too many new species to the human evolutionary tree. They say scientists have become too quick to call what may simply be an unusual individual a member of a whole new species.

"This will definitely be fuel for the splitters over those who see many specimens as evidence of a new species," said David Begun, an anthropologist at the University of Toronto.

The authors counter that since they submitted their paper they have found five to seven more remains in the cave site whose existence ranges from as long ago as 95,000 years ago to as recently as 13,000 years ago. The features of the new bones suggest they're of similar petite proportions. They add that characteristics seen in modern people who have pathologies causing a small brain were not evident in the ancient remains.

As for the little people's demise, geological records show there was a massive volcanic eruption on the island about 12,000 years ago, which could have eliminated any lingering populations. The first signs of modern man on the island date to just 11,000 years ago.

Roberts says the volcano could have "sealed the fate of the hobbits and the pygmy elephants." But local folk tales on the island of Flores hint that the small people may have persisted even longer.

"The stories suggest there may be more than a grain of truth to the idea that they were still living on Flores up until the Dutch arrived in the 1500s," Roberts said. "The stories suggest they lived in caves. The villagers would leave gourds with food out for them to eat, but legend has it these were the guests from hell -- they'd eat everything, including the gourds!"

So did the two human species meet and interact? For now a lack of evidence means we can only wonder -- and settle for the fictional tales of J.R.R. Tolkien.

There's a bit more about this discovery over at New Scientist. I can't help thinking about tiny body surfers and head lice.